Artificial blood vessel and method for making the same

ABSTRACT

An artificial blood vessel includes a nanofiber base film and a nanofiber external film connected to the nanofiber base film. The nanofiber base film comprises a plurality of polymer nanofibers aligned according to a first single-direction aligning pattern. The nanofiber external film comprises a plurality of polymer nanofibers aligned according to a second aligning pattern that is perpendicularly different from the first aligning pattern.

FIELD

The subject matter herein generally relates to medical technology, andmore particularly, to an artificial blood vessel and a method for makingthe artificial blood vessel.

BACKGROUND

Intravascular stents are generally tubular prosthesis that can be placedwithin a body passageway such as any vein, artery, or blood vesselwithin the vascular system. The intravascular stent usually containsendothelial cells. However, seeding the endothelial cells on the tubularintravascular stent is problematic.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by wayof example only, with reference to the attached figures.

FIG. 1 is a flowchart of an exemplary embodiment of a method for makingan artificial blood vessel.

FIG. 2 is a diagram of an electrospinning device used in the method inFIG. 1.

FIG. 3 is a diagram of a nanofiber base film made by the electrospinningdevice of FIG. 2.

FIG. 4 is a diagram showing a nanofiber deformable film formed on thenanofiber base film of FIG. 3, to form a nanofiber composite film.

FIG. 5 is a diagram showing the nanofiber composite film of FIG. 4 underultraviolet radiation, to form the artificial blood vessel.

FIG. 6 illustrates a reaction in the nanofiber composite film of FIG. 4,when under ultraviolet radiation.

FIG. 7 is a diagram showing the alignment of the nanofiber base film andthe nanofiber deformable film of nanofiber composite film of FIG. 4.

FIG. 8 is similar to FIG. 7, but showing the nanofiber base film and thenanofiber deformable film being aligned in a different way.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the embodiments described herein. The drawingsare not necessarily to scale, and the proportions of certain parts maybe exaggerated to better illustrate details and features of the presentdisclosure.

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

The term “comprising,” when utilized, means “including, but notnecessarily limited to”; it specifically indicates open-ended inclusionor membership in the so-described combination, group, series, and thelike.

FIG. 1 illustrates a flowchart of an embodiment for a method for makingan artificial blood vessel. The exemplary method is provided by way ofexample, as there are a variety of ways to carry out the method. Eachblock shown in the figure represents one or more processes, methods, orsubroutines, carried out in the exemplary method. Furthermore, theillustrated order of blocks is by example only, and the order of theblocks can change. Additional blocks may be added or fewer blocks may beutilized, without departing from this disclosure. The exemplary methodcan begin at block 101.

At block 101, referring to FIG. 2, an electrospinning device 1 isprovided that comprises a collector 2.

At block 102, referring to FIG. 3, a nanofiber base film 10 is formed onthe collector 2 through an electrospinning process. The nanofiber basefilm 10 comprises a number of polymer nanofibers aligned according to afirst aligning pattern. The first aligning pattern is that the polymerfibers of the nanofiber base film 10 are orderly aligned along a samedirection.

In at least one exemplary embodiment, the polymer nanofibers of thenanofiber base film 10 comprise polycaprolactone (PCL) nanofibers andpolyurethane (PU) nanofibers mixed together. The PCL nanofibers canprovide biodegradability, and the PU nanofibers can provide a highflexibility.

The nanofiber base film 10 can be formed by an electrospinning solutioncomprising PCL, PU, and a solvent. The solvent can be selected from agroup consisting of formic acid, acetic acid, acetone,dimethylformamide, dimethylacetamide, etrahydrofuran, dimethylsulfoxide, hexafluoroisopropanol, trifluoroethanol, dichloromethane,trichlormethane, methanol, ethanol, chlorotoluene, dioxane,trifluoroethane, trifluoroacetic acid, water, and any combinationthereof.

At block 103, referring to FIG. 4, a nanofiber deformable film 21 isformed on a surface of the nanofiber base film 10 facing away from thecollector 2 through an electrospinning process, thereby forming ananofiber composite film 30. The nanofiber deformable film 21 comprisesa number of polymer nanofibers aligned according to a second aligningpattern that is different from the first aligning pattern.

In at least one exemplary embodiment, the polymer nanofibers of thenanofiber deformable film 21 comprise photo-decomposable polymer. In atleast one exemplary embodiment, the polymer nanofibers of the nanofiberdeformable film 21 comprise coumarin-containing PCL nanofibers andcoumarin-containing PU nanofibers mixed together. The coumarin has achemical structure diagram of

The coumarin-containing PCL nanofibers and the coumarin-containing PUnanofibers have a chemical structure diagram of

The nanofiber deformable film 21 can be formed by an electrospinningsolution comprising coumarin-containing PCL, coumarin-containing PU, anda solvent. The solvent can be selected from a group consisting of formicacid, acetic acid, acetone, dimethylformamide, dimethylacetamide,etrahydrofuran, dimethyl sulfoxide, hexafluoroisopropanol,trifluoroethanol, dichloromethane, trichlormethane, methanol, ethanol,chlorotoluene, dioxane, trifluoroethane, trifluoroacetic acid, water,and any combination thereof.

At block 104, the nanofiber composite film 30 is separated from thecollector 2 and cut to a desired size. Endothelial cells can be seededon the nanofiber base film 10.

At block 105, the nanofiber composite film 30 after being cut is exposedto ultraviolet radiation. Thereby, the coumarin decomposes as shown inFIG. 6 to cause the nanofiber deformable film 21 to expand and roll toform a nanofiber external film 20 (FIG. 5). That is, the nanofibercomposite film 30 in FIG. 4 rolls to form the artificial blood vessel100.

Referring to FIG. 7, in at least one exemplary embodiment, the firstaligning pattern is that the polymer fibers of the nanofiber base film10 are orderly aligned along a same direction. The second aligningpattern is that the polymer fibers of the nanofiber deformable film 21are randomly aligned.

Referring to FIG. 8, in another exemplary embodiment, the first aligningpattern is that the polymer fibers of the nanofiber base film 10 areorderly aligned along a same direction (first direction). The secondaligning pattern is that the polymer fibers of the nanofiber deformablefilm 21 are orderly aligned along a second direction that isperpendicular to the first direction. The aligning pattern of thepolymer nanofibers can be controlled by adjusting the rotating speed ofthe collector 2. For example, the polymer nanofibers are randomlyaligned when the rotating speed of the collector 2 is 100 rpm. Thepolymer nanofibers are orderly aligned when the rotating speed of thecollector 2 is 1500 rpm. Furthermore, the thicknesses of the nanofiberbase film 10 and the nanofiber deformable film 21 can be controlled byadjusting the collecting time period of the collector 2.

The electrospinning process can be used to precisely control thealigning direction of the polymer nanofibers of the nanofiber base film10 and the nanofiber deformable film 21. Furthermore, when the polymernanofibers of the nanofiber base film 10 are controlled for alignmentalong the same direction, the rolling direction of the nanofiberdeformable film 21 can be controlled. Also, the desired degree ofrolling the nanofiber deformable film 21 (that is, the desired degree ofrolling the artificial blood vessel 100) is affected by the aligningpattern of the polymer nanofibers of the nanofiber deformable film 21.In detail, when the nanofiber deformable film 21 expands and rolls underthe ultraviolet radiation, the edges of the nanofiber deformable film 21that are parallel to the aligning direction of the polymer nanofibers ofthe nanofiber base film 10 are resistant to rolling. The edges of thenanofiber deformable film 21 that are perpendicular to the aligningdirection of the polymer nanofibers of the nanofiber base film 10 areless resistant to rolling. That is, the rolling direction of thenanofiber deformable film 21 should be perpendicular to the aligningdirection of the polymer nanofibers of the nanofiber base film 10.

Moreover, since the polymer nanofibers of the nanofiber base film 10 arealigned along the same direction, the artificial blood vessel 100 alsoextends along the same direction. When endothelial cells are seeded onthe nanofiber base film 10, the extending direction of the endothelialcells is also affected by the same direction, so that the endothelialcells can extend along the same direction. That is, the extendingdirection of the endothelial cells is the same as the direction of bloodflow when the artificial blood vessel 100 is in use.

In at least one exemplary embodiment, a surface of the nanofiberdeformable film 21 facing away from the nanofiber base film 10 isexposed to the ultraviolet radiation, thereby avoiding a decrease inactivity of the endothelial cells under the ultraviolet radiation.

Example 1

A nanofiber base film 10 was formed when the rotating speed of thecollector 2 was 1500 rpm and the collecting time period of the collector2 was 1 h. The nanofiber base film 10 comprised polymer nanofibersorderly aligned along a same direction, and had a thickness of 34 μm. Ananofiber deformable film 21 was formed on the nanofiber base film 10 toform a nanofiber composite film 30 when the rotating speed of thecollector 2 was 100 rpm and the collecting time period of the collector2 was 1.3 h. The nanofiber base film 10 comprised polymer nanofibersrandomly aligned. The nanofiber composite film 30 had a total thicknessof 84 The nanofiber composite film 30 was separated from the collector 2and cut to 20×1.5 cm², and was then exposed to ultraviolet radiation of254 nm for 1 second. An artificial blood vessel 100 was formed that hada diameter of 5 mm and a length of 20 cm.

Example 2

A nanofiber base film 10 was formed when the rotating speed of thecollector 2 was 1500 rpm and the collecting time period of the collector2 was 1 h. The nanofiber base film 10 comprised polymer nanofibersorderly aligned along a first direction, and had a thickness of 34 Thecollector 2 was rotated about 90 degrees. A nanofiber deformable film 21was formed on the nanofiber base film 10 to form a nanofiber compositefilm 30 when the rotating speed of the collector 2 was 1500 rpm and thecollecting time period of the collector 2 was 1.3 h. The nanofiber basefilm 10 comprised polymer nanofibers orderly aligned along a seconddirection perpendicular to the first direction. The nanofiber compositefilm 30 had a total thickness of 78 The nanofiber composite film 30 wasseparated from the collector 2 and cut to 15×1.5 cm², and was thenexposed to ultraviolet radiation of 254 nm for 0.5 second. An artificialblood vessel 100 was formed that had a diameter of 3 mm and a length of15 cm.

Example 3

A nanofiber composite film 30 was made according to the above EXAMPLE 2.Endothelial cells were seeded on the nanofiber base film 10. Thenanofiber composite film 30 was then exposed to ultraviolet radiation of254 nm for 0.5 second. An artificial blood vessel 100 was formed thathad a diameter of 5 mm and a length of 20 cm.

FIG. 5 illustrates an exemplary embodiment of an artificial blood vessel100. The artificial blood vessel 100 comprises a nanofiber base film 10and a nanofiber external film 20 connected to the nanofiber base film10. The nanofiber base film 10 is positioned at an inner side of theartificial blood vessel 100. The nanofiber external film 20 ispositioned at an outer side of the artificial blood vessel 100.

The nanofiber base film 10 comprises a number of polymer nanofibersaligned according to a first aligning pattern. The first aligningpattern is that the polymer fibers of the nanofiber base film 10 areorderly aligned along a same direction. In at least one exemplaryembodiment, the polymer nanofibers of the nanofiber base film 10comprise PCL nanofibers and PU nanofibers mixed together. Endothelialcells can be seeded on the nanofiber base film 10.

The nanofiber external film 20 comprises a number of polymer nanofibersaligned according to a second aligning pattern that is different fromthe first aligning pattern. The polymer nanofibers of the nanofiberexternal film 20 comprise PCL nanofibers and PU nanofibers mixedtogether.

With the above configuration, since the photo-decomposable polymer canbe decomposed under the ultraviolet radiation, the nanofiber deformablefilm 21 can expand and be rolled to form the artificial blood vessel100, to obtain a desired shape and a desired degree of rolling. Thus,the endothelial cells can be seeded before the nanofiber deformable film21 is rolled, thereby improving the operability for seeding theendothelial cells, comparing to seeding the endothelial cells on atubular intravascular stent. Furthermore, since the polymer nanofibersof the nanofiber base film 10 are aligned along the same direction, whenendothelial cells are seeded on the nanofiber base film 10, theendothelial cells can extend along the same direction. Moreover, thenanofiber composite film 30 can be cut according to a desired size ofthe artificial blood vessel 100. Thus, the size of the artificial bloodvessel 100 can be precisely controlled to satisfy different users.

Depending on the embodiment, certain of the steps of methods describedmay be removed, others may be added, and the sequence of steps may bealtered. It is also to be understood that the description and the claimsdrawn to a method may include some indication in reference to certainsteps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

It is to be understood, even though information and advantages of thepresent embodiments have been set forth in the foregoing description,together with details of the structures and functions of the presentembodiments, the disclosure is illustrative only; changes may be made indetail, especially in matters of shape, size, and arrangement of partswithin the principles of the present embodiments to the full extentindicated by the plain meaning of the terms in which the appended claimsare expressed.

What is claimed is:
 1. A method for making an artificial blood vessel comprising: providing an electrospinning device comprising a collector; forming a nanofiber base film on the collector through an electrospinning process, the nanofiber base film comprising a plurality of polymer nanofibers aligned according to a first aligning pattern, wherein the first aligning pattern is that the polymer fibers of the nanofiber base film are orderly aligned along a same direction; forming a nanofiber deformable film on a surface of the nanofiber base film facing away from the collector through an electrospinning process, thereby forming a nanofiber composite film, the nanofiber deformable film comprising a plurality of polymer nanofibers aligned according to a second aligning pattern that is different from the first aligning pattern, the polymer nanofibers of the nanofiber deformable film comprising photo-decomposable polymer; separating the nanofiber composite film from the collector and cutting the nanofiber composite film to a desired size; and exposing the nanofiber composite film after being cut to ultraviolet radiation, so that the photo-decomposable polymer decomposes to cause the nanofiber deformable film to expand and roll, thereby causing the nanofiber composite film to roll to form the artificial blood vessel.
 2. The method of claim 1, wherein the polymer nanofibers of the nanofiber base film comprise polycaprolactone nanofibers and polyurethane nanofibers mixed together.
 3. The method of claim 2, wherein the nanofiber base film is formed by an electrospinning solution comprising polycaprolactone, polyurethane, and a solvent.
 4. The method of claim 3, wherein the solvent is selected from a group consisting of formic acid, acetic acid, acetone, dimethylformamide, dimethylacetamide, etrahydrofuran, dimethyl sulfoxide, hexafluoroisopropanol, trifluoroethanol, dichloromethane, trichlormethane, methanol, ethanol, chlorotoluene, dioxane, trifluoroethane, trifluoroacetic acid, water, and any combination thereof.
 5. The method of claim 1, wherein the photo-decomposable polymer is coumarin, and the polymer nanofibers of the nanofiber deformable film comprise coumarin-containing polycaprolactone nanofibers and coumarin-containing polyurethane nanofibers mixed together.
 6. The method of claim 5, wherein the nanofiber deformable film is formed by an electrospinning solution comprising coumarin-containing polycaprolactone, coumarin-containing polyurethane, and a solvent.
 7. The method of claim 6, wherein The solvent is selected from a group consisting of formic acid, acetic acid, acetone, dimethylformamide, dimethylacetamide, etrahydrofuran, dimethyl sulfoxide, hexafluoroisopropanol, trifluoroethanol, dichloromethane, trichlormethane, methanol, ethanol, chlorotoluene, dioxane, trifluoroethane, trifluoroacetic acid, water, and any combination thereof.
 8. The method of claim 1, wherein before the step of exposing the nanofiber composite film after being cut to ultraviolet radiation further comprises: seeding endothelial cells on the nanofiber base film.
 9. The method of claim 8, wherein a surface of the nanofiber deformable film facing away from the nanofiber base film is exposed under the ultraviolet radiation.
 10. The method of claim 1, wherein the second aligning pattern is that the polymer fibers of the nanofiber deformable film are randomly aligned.
 11. The method of claim 1, wherein the first aligning pattern is that the polymer fibers of the nanofiber base film are orderly aligned along a first direction, and the second aligning pattern is that the polymer fibers of the nanofiber deformable film are orderly aligned along a second direction that is perpendicular to the first direction.
 12. An artificial blood vessel comprising: a nanofiber base film positioned at an inner side of the artificial blood vessel; and a nanofiber external film positioned at an outer side of the artificial blood vessel and connected to the nanofiber base film; wherein the nanofiber base film comprises a plurality of polymer nanofibers aligned according to a first aligning pattern, the first aligning pattern is that the polymer fibers of the nanofiber base film are orderly aligned along a same direction, the nanofiber external film comprises a plurality of polymer nanofibers aligned according to a second aligning pattern that is different from the first aligning pattern.
 13. The artificial blood vessel of claim 12, wherein the polymer nanofibers of the nanofiber base film comprise polycaprolactone nanofibers and polyurethane nanofibers mixed together.
 14. The artificial blood vessel of claim 12, wherein the polymer nanofibers of the nanofiber external film comprise polycaprolactone nanofibers and polyurethane nanofibers mixed together.
 15. The artificial blood vessel of claim 12, wherein endothelial cells are seeded on the nanofiber base film.
 16. A method for making an artificial blood vessel comprising: forming a nanofiber base film, the nanofiber base film comprising a plurality of polymer nanofibers aligned according to a first aligning pattern, wherein the first aligning pattern is that the polymer fibers of the nanofiber base film are orderly aligned along a same direction; forming a nanofiber deformable film on the nanofiber base film, thereby forming a nanofiber composite film, the nanofiber deformable film comprising a plurality of polymer nanofibers aligned according to a second aligning pattern that is different from the first aligning pattern, the polymer nanofibers of the nanofiber deformable film comprising photo-decomposable polymer; cutting the nanofiber composite film to a desired size; and exposing the nanofiber composite film after being cut to ultraviolet radiation, so that the photo-decomposable polymer decomposes to cause the nanofiber deformable film to expand and roll, thereby causing the nanofiber composite film to roll to form the artificial blood vessel. 